| Semi-submersible offshore platform is one of the main engineering structure for the development of marine resources.With the increasing demand for oil and gas resources,the development trend from shallow to deep water is inevitable,and the operational environment of the platform is getting worse.Therefore,under severe sea conditions,the motion response prediction of platform structure and mooring system under the excitation of wave and current loads has always been the focus of attention.Firstly,the accurate calculation of the hydrodynamic performance of the semi-submersible platform is performed firstly,where the three-dimensional Taylor expansion boundary element method is introduced in detail,and the numerical results are compared with the commercial software Aqwa and physical model test measurements.Then the dynamic response and computational efficiency of the mooring system are discussed.In the numerical algorithm,the catenary equations are applied to obtain the initial static configuration for the mooring lines,and then the Newmark iterative method is used for the dynamic solution of the mooring lines.The computational efficiency is greatly improved by using OpenMP parallel running lib.Finally,based on the asynchronous coupling method for the dynamic solution between the platform and mooring lines,the dynamic coupling analysis of the moored deep-water semi-submersible platform was carried out.Due to the viscous effect of the wave induced loads on the platform is important for the slowly varying drift motions especially in harsh sea conditions,Morison’s Equations are applied to predict the viscous wave load on the columns and pontoons.The applicability of two Morison models to simulate the viscous wave loads,and the Newman’s approximation of the platform’s vertical second-order low-frequency wave forces are discussed.On this basis,the analysis of a semi-submersible platform is carried out.The numerical analysis results were validated with the model test measurement. |
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